Effects of static electric fields on the photoionization spectra of two-electron atoms and ions

The simultaneous photoexcitation of two electrons is a highly correlated process, producing doubly excited states, observed as resonant structure in the ionization cross-section. This review paper explores the ability of a static electric field to affect these correlations, as evidenced by changes in the shape and energy of resonances. A comparison of field effects on the spectra of H−, Ps−, He, Ba and Cs− summarizes current understanding of the processes and the capability of theory to predict the cross-sectional features.